LOS ANGELES - An increase in emergency room visits for respiratory illnesses caused the Los Angeles County Department of Public Health today to urge residents to get vaccinated.

"We're approaching the time of year when we typically see peak numbers of flu cases," said Dr. Jonathan Fielding, director of the department. "The flu season does not end with the winter holidays, and flu can circulate as late as May." Emergency room visits for fever, cough and sore throats have been on the rise over the past several weeks, Fielding said. Most cases are caused by viruses other than influenza, but he said flu activity is increasing and expected to get worse over the next few weeks.

The flu vaccine takes two weeks to become effective.

Everyone over six months old should be vaccinated, according to the department, but those particularly at risk include:

-- pregnant women;

-- children younger than five years old;

-- adults age 65 or older;

-- those with chronic medical conditions such as heart disease or diabetes;

-- people living in nursing homes or long-term care facilities; and

-- those who care for at high-risk, including health care and day care workers.

Supermarkets and pharmacies offer low-cost vaccines and individuals without health insurance or a regular doctor can access free flu vaccine clinics operated by the county. Information is available at www.publichealth.lacounty.gov or by calling 211.

Influenza accounts for up to 200,000 hospitalizations and an average of 23,607 deaths in the U.S. each year, according to the Centers for Disease Control.